High-Tech Art Restoration Casts New Light on Master Works

Scientists have masterfully restored a series of badly damaged paintings by abstract expressionist Mark Rothko -- without laying a single paintbrush on them.

The method they chose, projecting colored light onto the paintings, is one of several cutting-edge techniques that can reveal the original appearance of old paintings. Describing these techniques at the 2014 AAAS Annual Meeting, a panel of experts noted that because these approaches don't alter the paintings themselves, they raise intriguing questions about what constitutes restoration.

Known as the Harvard Murals, the five massive Rothko paintings -- almost nine feet tall and in varying widths -- were installed in the penthouse dining room of Harvard University's Holyoke Center in 1963. Rothko used a non-permanent pigment called Lithol Red that was extremely light sensitive. As a result, the paintings faded so dramatically from sun exposure that the original crimson background later appeared light blue.

Considered unexhibitable, the paintings remained mostly in storage for the past few decades, according to Jens Stenger, a conservation scientist from Yale University who worked with the Harvard Art Museums on the project.

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The work couldn't be restored the conventional way. "It was painted very thinly so you would have to cover big portions of it with conservation paint, which removes the artist's hand," said Stenger. "The treatment would be irreversible, so it's not the ethical thing to do."

Drawing inspiration from a 1986 project, where a combination of blue and white light was used to compensate for the yellow varnish on a painting, Stenger tracked down color photographs of the murals from 1964. They, too, had faded.

With the help of colleagues at the MIT Media Lab and the University of Basel's Imaging and Medical Lab, Stenger first digitally restored the photographs and then, referencing colors from an uninstalled sixth panel of the series, built pixel-by-pixel a compensation image that was projected onto the original canvas to bring the viewers half a century back in time.

The work appears restored in the eye of the beholder, but is it?

"In many ways, treatment with conservation paint and treatment with light are very similar," Stenger said. To the naked eye, the sight of a red-painted surface and the sight of a white surface reflecting red light are not that different.

"It raises a lot of interesting questions," said Stenger. "Is the painting restored? The answer isn't so obvious."

For Richard Van Duyne and Joris Dik, high-tech art restoration literally takes on a different shade.

Van Duyne, a Northwestern University chemist who developed the world's most sensitive electron spectroscopy, used this technology to examine the chemical composition of molecules from Pierre-August Renoir's "Madame Léon Clapisson." He found, from a section of the canvas previously protected by the frame, that Renoir had used carmine lake, a brilliant but light-sensitive red pigment. The scientific investigation and subsequent digital restoration of what Renoir's original would have looked like is now the subject of a new exhibit at the Art Institute of Chicago.

Dik, from Delft University of Technology in the Netherlands, used micro X-rays to chart the distribution of grey crust formed on Van Gogh's 1887 painting "Flowers in a blue vase" as a result of oxidized cadmium yellow paint. The scanning also allowed him to replicate the surface structure to reconstruct, by 3D printing, the original color and texture of the painting.

These nano-scale techniques, said Van Duyne, also contribute to knowledge about the origins, technique and the feasibility for restoration of the paintings.

"Together with museum conservators, we're creating new ways of presenting the original appearance of paintings," said Dik. "We're not bound by ethical and technical limits of current methods."